Thermoluminescence dosimetry, commonly referred to as TLD, is a technique for radiation dose measurement. Thermoluminescence is an emission of light which occurs when thermoluminescent phosphors are heated after having been exposed to beta, gamma, X-ray or neutron radiation. TLD has several known advantages over other dosimetry techniques such as film dosimetry.
TLD systems have been developed for monitoring personnel who work in the vicinity of radiation materials, X-ray equipment, etc. In such systems, each person being monitored is given a badge to wear that consequently will be exposed to the same dosage of radiation as the person wearing the badge. Although different types of badges have been used, generally the badges consist of an outer holder which houses a TLD card insert usually containing two, three or four thermoluminescent (TL) elements in crystal form. The TLD cards and the holders as well may be provided with a machine readable code to enable card and/or holder identification.
Periodically the TLD cards are processed through a TLD card reader to obtain an exposure record for each person being monitored. In the TLD card reader, the TL elements in each card are heated and the thermoluminescence is measured as by using a photomultiplier tube and associated electronic analysis circuitry to provide a read-out of the TL integrals and/or glow curve. Some TLD card readers require manual loading of each TL card whereas others include card transport assemblies for automatic processing of a batch of TLD cards that have been removed from their holders. Also known is a TLD card reader which can process the TLD cards without having to remove them from their holders. As is known, TLD cards or holders with the TLD cards may be loaded into one or more cartridges or magazines depending on the particular type of reader being employed.